Croup

Croup, or laryngotracheobronchitis, is an infection of the trachea
(the upper part of the windpipe, just below the vocal cords) which often also
involves the vocal cords themselves as well as the large air passages in the
lung.

Croup is usually caused by a viral infection. Back when
measles was common,
the measles virus often caused croup. Now that we
immunize against
measles, we hardly ever see it in the United States -- when we do see it,
it is in children who did not receive the vaccine (another reason to
immunize). The most common cause of croup nowadays are the
parainfluenza viruses, which despite their name are not related to
influenza (in fact, the
two families of viruses are very different in structure and function). There
are several different types of parainfluenza viruses. Unfortunately we do not
yet have vaccines for any of them. The
influenza viruses can
also cause croup, as can the
adenoviruses

When you get croup, you usually start out with
cold symptoms: cough,
congestion, and a runny nose with clear discharge. As the trachea's walls
swell, the inside of the trachea narrows. Unlike
asthma, where the small air
passages in the lung become inflamed and narrow, croup does not make it hard
to breathe out. (The wheezing of asthma is caused by air being forced out
through the narrowed small airways.) In croup, the narrow trachea makes it
hard to inhale, and you can hear a wheezing-like sound, or
stridor, when you try to inhale. The swelling of the vocal cords makes
you hoarse, and can make you sound like a seal barking. With bigger people
(adolescents and adults) the trachea is large enough that breathing isn't
affected as much as in small children, but the inflammation of the vocal cords
results in laryngitis (you can't talk).

Since it's caused by a virus, there is no medicine that can stop croup
completely. The first thing I usually suggest when a patient of mine has a
croupy cough is to turn on the shower in your bathroom as hot as it will go,
steam up the bathroom thoroughly, and then take your child into the steamy
bathroom (not under the hot water!) and let him/her breath the steam.
Another tactic is to breathe the mist from a cool-mist humidifier; the
moisture helps soothe the inflamed mucous membranes in the airways. A
third method is to let your child breathe cold air, such as outside air
in winter. (Often parents will take their child to the emergency room for bad
croup, and the cold air from the trip outside is enough to relieve the
swelling.)
If those methods do not work, there are medicines which will reduce the
swelling. (This is similar to the treatment for asthma, but the medicines used
for asthma do not necessarily work on croup. NEVER use a
medicine for something other than what your doctor prescribed it for without
asking your doctor first!)

Occasionally croup can make it so hard to breathe that a child may not be
getting enough air; this is one reason why we sometimes have to put "croupers"
in the hospital. Often we put children who are admitted for croup in a
"cool-mist tent" (with oxygen if needed), and give the medicines I mentioned
above. Usually, though, the steamy bathroom and the cool-mist humidifier work
pretty well. I usually tell the parents of my patients to call me if their
children are still having a lot of coughing after the steamy bathroom.

PLEASE NOTE: As with all of this Web site, I try to give
general answers to common questions my patients and their parents ask me
in my (real) office. If you have specific questions about your
child you must ask your child's regular doctor. No doctor can give
completely accurate advice about a particular child without knowing and
examining that child. I will be happy to try and answer
general questions
about children's health, but unless your child is a regular patient of
mine I cannot give you specific advice.